The present invention relates to towed air target and including particularly a bag to be towed through a towing cable by an aircraft; the bag to be provided with metallic fibres for radar acquisition and further including a sound receiver which responds to compression or shock waves resulting from a passing projectile. The equipment further includes evaluating circuitry for ascertaining the trajectory of the projectile.
Devices of the kind to which the invention pertains are known generally. The towed bag serves as an optical target or a target to be detected through radar. The sound receiver is a pressure sensitive and measuring device responding to shock waves of passing projectiles, and the sound pattern can be used in order to acquire information about the trajectory of the projectile as it passes the target. The pressure or shock signals as detected are converted into electrical signals and through a signal line included in the towing cable these signals are transmitted to the towing craft to be evaluated by suitable electronic equipment on board of the craft. In practice, however, it was found that the acoustic "target" defined by the sound detector and the optical or radar target do not agree so that in relatively small distance ranges the measuring results are incorrect.